[arch-projects] [devtools] [PATCH 5/9] arch-nspawn: Avoid errors where $working_dir is longer than HOST_NAME_MAX.

[Luke Shumaker]

Currently, if absolute path of the chroot directory is more than 65 bytes
(HOST_NAME_MAX+1) long, arch-nspawn will fail (mysteriously too, since
stderr is directed to /dev/null).

This patch makes it so that if $machine_name is more than 64
(HOST_NAME_MAX) bytes long, it is stripped to use just the last 64 bytes.

I left in a comment that would have it find HOST_NAME_MAX dynamically, but
have it just hard-coded as '64'; the script already isn't portable away
from systemd/Linux, and it likely won't change on Linux anytime soon.
---
 arch-nspawn.in | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch-nspawn.in b/arch-nspawn.in
index 15db2e9..df3a08f 100644
--- a/arch-nspawn.in
+++ b/arch-nspawn.in
@@ -96,6 +96,12 @@ eval $(grep '^CARCH=' "$working_dir/etc/makepkg.conf")
 
 machine_name="${working_dir//[![:alnum:]_-]/-}"
 machine_name="${machine_name#-}"
+#HOST_NAME_MAX="$(printf '%s\n' '#include <limits.h>' 'HOST_NAME_MAX'|cpp -|sed -n '$p')"
+HOST_NAME_MAX=64
+if [[ ${#machine_name} -gt "$HOST_NAME_MAX" ]]; then
+	machine_name="${machine_name:(-${HOST_NAME_MAX})}"
+	machine_name="${machine_name#-}"
+fi
 
 exec ${CARCH:+setarch "$CARCH"} systemd-nspawn 2>/dev/null \
 	-D "$working_dir" \
-- 
1.9.2